I guess it all depends on how many miles have been driven. I believe 15k miles (OM616/617) is the valve adjustment interval. In this case, it can't hurt

I don't think you'll be able to tell if the valves need adjustment externally, other than secondary symptoms - hard starting, rough idle, etc. Gotta check them with a feeler gauge

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1982 240D, sold 9/17/2008
1987 300D TurboW124.133 - 603.960, 722.317 - Smoke Silver Metallic / Medium Red (702/177), acquired 8/15/2009
262,715 and counting